Terminal apparatus, base station apparatus, and communication method

ABSTRACT

A terminal apparatus is a terminal apparatus for communicating via a primary cell and a secondary cell, the terminal apparatus including: a receiver configured to receive an activation/deactivation MAC CE indicating activation of the secondary cell; and a medium access control layer processing unit configured to: activate a first downlink BWP in multiple downlink BWPs in a case that the activation/deactivation MAC CE is received and the secondary cell is not activated; and not to activate the first downlink BWP in a case that the activation/deactivation MAC CE is received, the secondary cell is activated, and a second downlink BWP of the secondary cell is activated. The first downlink BWP is different from the second downlink BWP.

TECHNICAL FIELD

The present invention relates to a terminal apparatus, a base stationapparatus, and a communication method.

This application claims priority to JP 2017-203695 filed on Oct. 20,2017, the contents of which are incorporated herein by reference.

BACKGROUND ART

A radio access method and a radio network for cellular mobilecommunications (hereinafter, referred to as “Long Term Evolution (LTE:Registered Trademark)”, or “Evolved Universal Terrestrial Radio Access(EUTRA)”) have been studied in the 3rd Generation Partnership Project(3GPP). In 3GPP, a new radio access method (hereinafter referred to as“New Radio (NR)”) has been studied. In LTE, a base station apparatus isalso referred to as an evolved NodeB (eNodeB). In NR, a base stationapparatus is also referred to as a gNodeB. In LTE, and in NR, a terminalapparatus is also referred to as a User Equipment (UE). LTE, as well asNR, is a cellular communication system in which multiple areas aredeployed in a cellular structure, with each of the multiple areas beingcovered by a base station apparatus. A single base station apparatus maymanage multiple cells.

In NR, a set of bandwidth parts (BWPs) is configured for one servingcell (NPL 3). The terminal apparatus receives a PDCCH and a PDSCH in theBWPs.

CITATION LIST Non Patent Literature

-   NPL 1: “3GPP TS 38.211 V1.0.0 (2017-09), NR; Physical channels and    modulation”, 7 Sep. 2017.-   NPL 2: “3GPP TS 38.212 V1.0.0 (2017-09), NR; Multiplexing and    channel coding”, 7 Sep. 2017.-   NPL 3: “3GPP TS 38.213 V1.0.1 (2017-09), NR; Physical layer    procedures for control”, 7 Sep. 2017.-   NPL 4: “3GPP TS 38.214 V1.0.1 (2017-09), NR; Physical layer    procedures for data”, 7 Sep. 2017.

SUMMARY OF INVENTION Technical Problem

One aspect of the present invention provides a terminal apparatuscapable of efficiently performing reception of downlink transmission, acommunication method used for the terminal apparatus, a base stationapparatus capable of efficiently performing downlink transmission, and acommunication method used for the base station apparatus.

Solution to Problem

(1) According to some aspects of the present invention, the followingmeasures are provided. Specifically, a first aspect of the presentinvention is a terminal apparatus that performs communication via aprimary cell and a secondary cell, the terminal apparatus including: areceiver configured to receive an activation/deactivation Medium AccessControl (MAC) Control Element (CE) indicating activation of thesecondary cell; and a medium access control layer processing unitconfigured to: activate a first downlink bandwidth part (BWP) inmultiple downlink BWPs included in the secondary cell in a case that theactivation/deactivation MAC CE is received and the secondary cell is notactivated; and not to activate the first downlink BWP in a case that theactivation/deactivation MAC CE is received, the secondary cell isactivated, and a second downlink BWP of the secondary cell is activated.In the terminal apparatus, the first downlink BWP is different from thesecond downlink BWP.

(2) A second aspect of the present invention is a terminal apparatus,wherein activating the first downlink BWP is indicated by a RadioResource Control (RRC) message received from a base station apparatus.

(3) A third aspect of the present invention is a base station apparatusthat performs communication via a primary cell and a secondary cell, thebase station apparatus including: a transmitter configured to transmitan activation/deactivation Medium Access Control (MAC) Control Element(CE) indicating activation of the secondary cell to a terminalapparatus; and a medium access control layer processing unit configuredto control a downlink bandwidth part (BWP) to be activated in multipledownlink BWPs included in the secondary cell by transmitting theactivation/deactivation MAC CE, wherein a first downlink BWP in themultiple downlink BWPs is activated by the terminal apparatus in a casethat the terminal apparatus receives the activation/deactivation MAC CEand the secondary cell is not activated, and the first downlink BWP inthe multiple downlink BWPs is not activated by the terminal apparatus ina case that the terminal apparatus receives the activation/deactivationMAC CE, the secondary cell is activated, and a second downlink BWP ofthe secondary cell is activated. In the base station apparatus, thefirst downlink BWP is different from the second downlink BWP.

(4) A fourth aspect of the present invention is a base stationapparatus, wherein activating the first downlink BWP is indicated bytransmitting a Radio Resource Control (RRC) message.

(5) A fifth aspect of the present invention is a communication methodused for a terminal apparatus that performs communication via a primarycell and a secondary cell, the communication method including the stepsof: receiving an activation/deactivation Medium Access Control (MAC)Control Element (CE) indicating activation of the secondary cell;activating a first downlink bandwidth part (BWP) in multiple downlinkBWPs included in the secondary cell in a case that theactivation/deactivation MAC CE is received and the secondary cell is notactivated; and not activating the first downlink BWP in a case that theactivation/deactivation MAC CE is received, the secondary cell isactivated, and a second downlink BWP of the secondary cell is activated,wherein the first downlink BWP is different from the second downlinkBWP.

(6) A sixth aspect of the present invention is a communication methodused for a base station apparatus that performs communication via aprimary cell and a secondary cell, the communication method includingthe steps of: transmitting an activation/deactivation Medium AccessControl (MAC) Control Element (CE) indicating activation of thesecondary cell to a terminal apparatus; and controlling a downlinkbandwidth part (BWP) to be activated in multiple downlink BWPs includedin the secondary cell by transmitting the activation/deactivation MACCE, wherein a first downlink BWP in the multiple downlink BWPs isactivated by the terminal apparatus in a case that the terminalapparatus receives the activation/deactivation MAC CE and the secondarycell is not activated, the first downlink BWP in the multiple downlinkBWPs is not activated by the terminal apparatus in a case that theterminal apparatus receives the activation/deactivation MAC CE, thesecondary cell is activated, and a second downlink BWP of the secondarycell is activated, and the first downlink BWP is different from thesecond downlink BWP.

Advantageous Effects of Invention

According to one aspect of the present invention, the terminal apparatuscan efficiently perform reception of downlink transmission. The basestation apparatus can efficiently perform downlink transmission.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a conceptual diagram of a radio communication system accordingto the present embodiment.

FIG. 2 is a diagram illustrating a schematic configuration of a radioframe according to the present embodiment.

FIG. 3 is a diagram illustrating a schematic configuration of an uplinkslot according to the present embodiment.

FIG. 4 is a schematic block diagram illustrating a configuration of aterminal apparatus 1 according to the present embodiment.

FIG. 5 is a schematic block diagram illustrating a configuration of abase station apparatus 3 according to the present embodiment.

FIG. 6 is a diagram illustrating a sequence chart related to aconfiguration of a serving cell and a downlink BWP according to thepresent embodiment.

FIG. 7 is a diagram illustrating a flow related to activation of asecondary cell according to the present embodiment.

FIG. 8 is a diagram illustrating an example of a downlink BWP of asecondary cell according to the present embodiment.

FIG. 9 is a diagram illustrating an example of a CORESET according tothe present embodiment.

FIG. 10 is a diagram illustrating an example of a search space accordingto the present embodiment.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be described below.

FIG. 1 is a conceptual diagram of a radio communication system accordingto the present embodiment. In FIG. 1, the radio communication systemincludes a terminal apparatus 1 and a base station apparatus 3.

Physical channels and physical signals according to the presentembodiment will be described.

In uplink radio communication from the terminal apparatus 1 to the basestation apparatus 3, the following uplink physical channels are used.The uplink physical channels are used for transmitting informationoutput from a higher layer.

-   -   Physical Uplink Control Channel (PUCCH)    -   Physical Uplink Shared Channel (PUSCH)    -   Physical Random Access Channel (PRACH)

The PUCCH is used for transmitting Channel State Information (CSI) ofthe downlink, and/or, Hybrid Automatic Repeat reQuest (HARQ-ACK). TheCSI, as well as the HARQ-ACK, is Uplink Control Information (UCI).

The PUSCH is used for transmitting uplink data (Transport block,Uplink-Shared Channel (UL-SCH)), the CSI of the downlink, and/or theHARQ-ACK. The CSI, as well as the HARQ-ACK, is Uplink ControlInformation (UCI). The terminal apparatus 1 may transmit the PUSCH,based on detection of Physical Downlink Control Channel (PDCCH)including an uplink grant.

The PRACH is used to transmit a random access preamble.

The following uplink physical signal is used in the uplink radiocommunication. The uplink physical signal is not used for transmittinginformation output from a higher layer, but is used by a physical layer.

-   -   Demodulation Reference Signal (DMRS)

The DMRS is associated with transmission of the PUSCH or the PUCCH. TheDMRS may be time-multiplexed with the PUSCH. The base station apparatus3 may use the DMRS in order to perform channel compensation of thePUSCH.

The following downlink physical channels are used for downlink radiocommunication from the base station apparatus 3 to the terminalapparatus 1. The downlink physical channels are used for transmittinginformation output from the higher layer.

-   -   Physical Downlink Control Channel (PDCCH)    -   Physical Downlink Shared Channel (PDSCH)

The PDCCH is used to transmit Downlink Control Information (DCI). Thedownlink control information is also referred to as a DCI format. Thedownlink control information includes an uplink grant. The uplink grantmay be used for scheduling of a single PUSCH within a single cell. Theuplink grant may be used for scheduling multiple PUSCHs in multipleslots within a single cell. The uplink grant may be used for schedulinga single PUSCH in multiple slots within a single cell.

The PDSCH is used to transmit downlink data (Transport block,Downlink-Shared Channel (DL-SCH)).

The UL-SCH and the DL-SCH are transport channels. A channel used in aMedium Access Control (MAC) layer is referred to as a transport channel.A unit of the transport channel used in the MAC layer is also referredto as a transport block (TB) or a MAC Protocol Data Unit (PDU).

Hereinafter, carrier aggregation will be described.

According to the present embodiment, one or multiple serving cells areconfigured for the terminal apparatus 1. A technology in which theterminal apparatus 1 communicates via the multiple serving cells isreferred to as cell aggregation or carrier aggregation. An aspect of thepresent invention may be applied to each of the multiple serving cellsconfigured for the terminal apparatus 1. An aspect of the presentinvention may be applied to some of the multiple serving cellsconfigured. The multiple serving cells includes at least one primarycell. Here, the multiple serving cells may include at least one ofmultiple secondary cells.

The primary cell is a serving cell in which an initial connectionestablishment procedure has been performed, a serving cell in which aconnection re-establishment procedure has been initiated, or a cellindicated as a primary cell in a handover procedure. The secondary cellmay be configured at a point of time when or after a Radio ResourceControl (RRC) connection is established.

A carrier corresponding to a serving cell in the downlink is referred toas a downlink component carrier. A carrier corresponding to a servingcell in the uplink is referred to as an uplink component carrier. Thedownlink component carrier and the uplink component carrier arecollectively referred to as a component carrier.

The terminal apparatus 1 can perform simultaneous transmission and/orreception on multiple physical channels in multiple serving cells(component carriers). A single physical channel is transmitted in asingle serving cell (component carrier) out of the multiple servingcells (component carriers).

A set of downlink bandwidth parts (BWPs) may be configured for eachserving cell. The set of downlink BWPs may include one or multipledownlink BWPs. The downlink BWP included in the set of downlink BWPs forthe serving cell is also referred to as the downlink BWP in the servingcell or the downlink BWP included in the serving cell. One physicalchannel is transmitted in one downlink BWP out of multiple downlinkBWPs. One downlink BWP may be constituted by multiple continuousphysical resource blocks in the frequency domain.

A configuration of the radio frame according to the present embodimentwill be described below.

FIG. 2 is a diagram illustrating a schematic configuration of a radioframe according to the present embodiment. In FIG. 2, the horizontalaxis is a time axis. Each of the radio frames may be 10 ms in length.Each of the radio frames may include ten slots. Each of the slots may be1 ms in length.

An example of a configuration of a slot according to the presentembodiment will be described below. FIG. 3 is a diagram illustrating aschematic configuration of an uplink slot according to the presentembodiment. FIG. 3 illustrates a configuration of an uplink slot in acell. In FIG. 3, the horizontal axis is a time axis, and the verticalaxis is a frequency axis. The uplink slot may include N^(UL) _(symb)SC-FDMA symbols. The uplink slot may include N^(UL) _(symb) OFDMsymbols. Hereinafter, a case that the uplink slot includes OFDM symbolswill be described in the present embodiment, but the present embodimentcan be applied to a case that the uplink slot includes SC-FDMA symbols.

In FIG. 3, l is an OFDM symbol number/index, and k is a subcarriernumber/index. The physical signal or the physical channel transmitted ineach of the slots is expressed by a resource grid. In the uplink, theresource grid is defined by multiple subcarriers and multiple OFDMsymbols. Each element within the resource grid is referred to as aresource element. The resource element is expressed by a subcarriernumber/index k and an OFDM symbol number/index l.

The uplink slot includes the multiple OFDM symbols l (l=0, 1, . . . ,N^(UL) _(symb)) in the time domain. For a normal Cyclic Prefix (CP) inthe uplink, N^(UL) _(symb) may be 7 or 14. For an extended CP in theuplink, N^(UL) _(symb) may be 6 or 12.

The terminal apparatus 1 receives the parameter UL-CyclicPrefixLength ofthe higher layer indicating the CP length in the uplink from the basestation apparatus 3. The base station apparatus 3 may broadcast, in thecell, system information including the parameter UL-CyclicPrefixLengthof the higher layer corresponding to the cell.

The uplink slot includes the multiple subcarriers k (k=0, 1, . . . ,N^(UL) _(RB)*N^(RB) _(SC)) in the frequency domain. N^(UL) _(RB) is anuplink bandwidth configuration for the serving cell expressed by amultiple of N^(RB) _(SC). N^(RB) _(SC) is the (physical) resource blocksize in the frequency domain expressed by the number of subcarriers. Thesubcarrier spacing Δf may be 15 kHz. The N^(RB) _(SC) may be 12. The(physical) resource block size in the frequency domain may be 180 kHz.

One physical resource block is defined by N^(UL) _(symb) continuous OFDMsymbols in the time domain and by N^(RB) _(SC) continuous subcarriers inthe frequency domain. Hence, one physical resource block is constitutedby (N^(UL) _(symb)*N^(RB) _(SC)) resource elements. One physicalresource block may correspond to one slot in the time domain. Thephysical resource blocks may be numbered n_(RRB) (0, 1, . . . , N^(UL)_(RB)−1) in the ascending order of frequencies in the frequency domain.

The downlink slot according to the present embodiment includes multipleOFDM symbols. Since the configuration of the downlink slot according tothe present embodiment is basically the same as the configuration of theuplink slot, the description of the configuration of the downlink slotwill be omitted.

Configurations of apparatuses according to the present embodiment willbe described below.

FIG. 4 is a schematic block diagram illustrating a configuration of theterminal apparatus 1 according to the present embodiment. Asillustrated, the terminal apparatus 1 includes a radio transmissionand/or reception unit 10 and a higher layer processing unit 14. Theradio transmission and/or reception unit 10 includes an antenna unit 11,a Radio Frequency (RF) unit 12, and a baseband unit 13. The higher layerprocessing unit 14 includes a medium access control layer processingunit 15 and a radio resource control layer processing unit 16. The radiotransmission and/or reception unit 10 is also referred to as atransmitter, a receiver, a coding unit, a decoding unit, or a physicallayer processing unit.

The higher layer processing unit 14 outputs uplink data (transportblock) generated by a user operation or the like, to the radiotransmission and/or reception unit 10. The higher layer processing unit14 performs processing of the Medium Access Control (MAC) layer, thePacket Data Convergence Protocol (PDCP) layer, the Radio Link Control(RLC) layer, and the Radio Resource Control (RRC) layer.

The medium access control layer processing unit 15 included in thehigher layer processing unit 14 performs processing of the Medium AccessControl layer. The medium access control layer processing unit 15controls random access procedure in accordance with the variousconfiguration information/parameters managed by the radio resourcecontrol layer processing unit 16.

The radio resource control layer processing unit 16 included in thehigher layer processing unit 14 performs processing of the RadioResource Control layer. The radio resource control layer processing unit16 manages various types of configuration information/parameters of theterminal apparatus 1. The radio resource control layer processing unit16 sets various types of configuration information/parameters, based ona higher layer signal received from the base station apparatus 3.Namely, the radio resource control layer processing unit 16 sets thevarious configuration information/parameters in accordance with theinformation for indicating the various configurationinformation/parameters received from the base station apparatus 3.

The radio transmission and/or reception unit 10 performs processing ofthe physical layer, such as modulation, demodulation, coding, decoding,and the like. The radio transmission and/or reception unit 10demultiplexes, demodulates, and decodes a signal received from the basestation apparatus 3, and outputs the information resulting from thedecoding to the higher layer processing unit 14. The radio transmissionand/or reception unit 10 generates a transmit signal by modulating andcoding data, and performs transmission to the base station apparatus 3.

The RF unit 12 converts (down converts) a signal received via theantenna unit 11 into a baseband signal by orthogonal demodulation andremoves unnecessary frequency components. The RF unit 12 outputs aprocessed analog signal to the baseband unit.

The baseband unit 13 converts the analog signal input from the RF unit12 into a digital signal. The baseband unit 13 removes a portioncorresponding to a Cyclic Prefix (CP) from the digital signal resultingfrom the conversion, performs Fast Fourier Transform (FFT) of the signalfrom which the CP has been removed, and extracts a signal in thefrequency domain.

The baseband unit 13 generates an SC-FDMA symbol by performing InverseFast Fourier Transform (IFFT) of the data, adds CP to the generatedSC-FDMA symbol, generates a baseband digital signal, and converts thebaseband digital signal into an analog signal. The baseband unit 13outputs the analog signal resulting from the conversion, to the RF unit12.

The RF unit 12 removes unnecessary frequency components from the analogsignal input from the baseband unit 13 using a low-pass filter,up-converts the analog signal into a signal of a carrier frequency, andtransmits the up-converted signal via the antenna unit 11. The RF unit12 amplifies power. The RF unit 12 may have a function of controllingtransmit power. The RF unit 12 is also referred to as a transmit powercontrol unit.

FIG. 5 is a schematic block diagram illustrating a configuration of thebase station apparatus 3 according to the present embodiment. Asillustrated, the base station apparatus 3 includes a radio transmissionand/or reception unit 30 and a higher layer processing unit 34. Theradio transmission and/or reception unit 30 includes an antenna unit 31,an RF unit 32, and a baseband unit 33. The higher layer processing unit34 includes a medium access control layer processing unit 35 and a radioresource control layer processing unit 36. The radio transmission and/orreception unit 30 is also referred to as a transmitter, a receiver, acoding unit, a decoding unit, or a physical layer processing unit.

The higher layer processing unit 34 performs processing of the MediumAccess Control (MAC) layer, the Packet Data Convergence Protocol (PDCP)layer, the Radio Link Control (RLC) layer, and the Radio ResourceControl (RRC) layer.

The medium access control layer processing unit 35 included in thehigher layer processing unit 34 performs processing of the Medium AccessControl layer. The medium access control layer processing unit 35controls random access procedure in accordance with the variousconfiguration information/parameters managed by the radio resourcecontrol layer processing unit 36.

The radio resource control layer processing unit 36 included in thehigher layer processing unit 34 performs processing of the RadioResource Control layer. The radio resource control layer processing unit36 generates, or acquires from a higher node, downlink data (transportblock) allocated on a physical downlink shared channel, systeminformation, an RRC message, a MAC Control Element (CE), and the like,and performs output to the radio transmission and/or reception unit 30.The radio resource control layer processing unit 36 manages varioustypes of configuration information/parameters for each of the terminalapparatuses 1. The radio resource control layer processing unit 36 mayset various types of configuration information/parameters for each ofthe terminal apparatuses 1 via higher layer signaling. That is, theradio resource control layer processing unit 36 transmits/broadcastsinformation for indicating various types of configurationinformation/parameters.

The functionality of the radio transmission and/or reception unit 30 issimilar to the functionality of the radio transmission and/or receptionunit 10, and hence description thereof is omitted.

Each of the units having the reference signs 10 to 16 included in theterminal apparatus 1 may be configured as a circuit. Each of the unitshaving the reference signs 30 to 36 included in the base stationapparatus 3 may be configured as a circuit. Each of the units having thereference signs 10 to 16 included in the terminal apparatus 1 may beconfigured as at least one processor and a memory coupled to the atleast one processor. Each of the units having the reference signs 30 to36 included in the base station apparatus 3 may be configured as atleast one processor and a memory coupled to the at least one processor.

FIG. 6 is a diagram illustrating a sequence chart related to aconfiguration of a serving cell and a downlink BWP according to thepresent embodiment.

In 600, the terminal apparatus 1 performs an initial connectionestablishment procedure, a connection re-establishment procedure, or ahandover procedure in the initial downlink BWP in the primary cell.

In 604, the terminal apparatus 1 receives theRRCConnectionReconfiguration message 605. TheRRCConnectionReconfiguration message 605 may include configurationinformation of a set of downlink BWPs for the primary cell, a secondarycell, and a set of downlink BWPs for the secondary cell. The terminalapparatus 1 may configure, based on the configuration information, theset of downlink BWPs for the primary cell, the secondary cell, and theset of downlink BWPs for the secondary cell.

In 607, the terminal apparatus 1 transmits an RRCConnectionCompletemessage 607 after the configuration based on theRRCConnectionReconfiguration message 605 is completed.

Hereinafter, the activation of the downlink BWP will be described.

Activating the downlink BWP means applying the monitoring of the PDCCHin the downlink BWP.

At one point of time, at most one downlink BWP may be activated in oneserving cell. Namely, multiple downlink BWPs are not simultaneouslyactivated in one serving cell.

One downlink BWP may always be activated in the primary cell. All thedownlink BWPs may not be activated in the secondary cell. The servingcell including an activated downlink BWP is also referred to as anactivated serving cell. A serving cell not including an activateddownlink BWP is also referred to as a deactivated serving cell. Asecondary cell including an activated downlink BWP is also referred toas an activated secondary cell. A secondary cell not including anactivated downlink BWP is also referred to as a deactivated secondarycell. In other words, the primary cell is always activated. Activatingany downlink BWP in a secondary cell in which no downlink BWP isactivated means activating the secondary cell. Deactivating all theactivated downlink BWPs in the secondary cell means deactivating thesecondary cell.

The initial downlink BWP in the primary cell may be activated until aset of downlink BWPs is configured for the primary cell. Based on theset of the downlink BWPs being configured for the primary cell, theinitial downlink BWP may be deactivated and any one of the downlink BWPsin the set of the downlink BWPs for the primary cell may be activated.The RRCConnectionReconfiguration message 605 may include informationindicating a downlink BWP to be activated based on the set of downlinkBWPs being configured for the primary cell. Deactivating the activateddownlink BWP and activating the deactivated downlink BWP means switchingof the activated downlink BWP from a downlink BMP to another downlinkBWP.

At the time when the secondary cell is added, all the downlink BWPs inthe secondary cell may be deactivated. The base station apparatus 3 canactivate and deactivate the configured secondary cell by transmittingactivation/deactivation Medium Access Control (MAC) Control Element(CE). The activation/deactivation MAC CE is MAC layer controlinformation. The terminal apparatus 1 may transmit, to the base stationapparatus 3, a HARQ-ACK for the PDSCH including theactivation/deactivation MAC CE, by using the PUCCH.

The terminal apparatus 1 may activate the configured secondary cell,based on the reception of the activation/deactivation MAC CE indicatingactivation of the configured serving cell. The terminal apparatus 1 maydeactivate the configured secondary cell, based on the reception of theactivation/deactivation MAC CE indicating deactivation of the configuredserving cell.

FIG. 7 is a diagram illustrating a flow related to activation of asecondary cell according to the present embodiment.

In 700, the terminal apparatus 1 receives the activation/deactivationMAC CE indicating the activation of the secondary cell.

The set of downlink BWPs for the secondary cell may include one defaultdownlink BWP and one or multiple non-default downlink BWPs. Thenon-default downlink BWP in the secondary cell is also referred to as adownlink BWP other than the default downlink BWP out of the multipledownlink BWPs in the secondary cell. The RRCConnectionReconfigurationmessage 605 may include information indicating a default downlink BWPand/or a non-default downlink BWP in the secondary cell.

In 702, the terminal apparatus 1 may determine whether the non-defaultdownlink BWP in the secondary cell is activated.

(702-1) In a case that the non-default downlink BWP in the secondarycell is not activated, the terminal apparatus 1 may activate the defaultdownlink BWP in the secondary cell and finish the process related toactivation of the secondary cell.

(702-2) In a case that the non-default downlink BWP in the secondarycell is activated, the terminal apparatus 1 may end the processingrelated to the activation of the secondary cell without activating thedefault downlink BWP in the secondary cell.

In 702, the terminal apparatus 1 may determine whether any downlink BWPin the secondary cell is activated.

(702-1) In a case that none of the downlink BWPs in the secondary cellis activated, the terminal apparatus 1 may activate the default downlinkBWP in the secondary cell and finish the processing relating toactivation of the secondary cell.

(702-2) In a case that any one of the downlink BWPs in the secondarycell is activated, the terminal apparatus 1 may finish the processingrelated to the activation of the secondary cell without activating thedefault downlink BWP in the secondary cell.

The base station apparatus 3 can perform switching of the activateddownlink BWP from a downlink BMP to another downlink BWP by transmittingthe downlink control information. An index may be allocated to thedownlink BWP. The downlink control information may include BWP indexinformation indicating the index of the downlink BWP. The downlinkcontrol information may include information indicating resourcesallocated for the PDSCH in the downlink BWP indicated by the BWP indexinformation.

In a case that the terminal apparatus 1 receives the downlink controlinformation including the BWP index information indicating thedeactivated downlink BWP in the serving cell including the activateddownlink BWP, the terminal apparatus 1 may perform switching of theactivated downlink BWP in the serving cell from a downlink BMP toanother downlink BWP indicated by information indicating the downlinkBWP.

In a case that, in an activated downlink BWP in a certain serving cell,the terminal apparatus 1 receives downlink control information includingBWP index information indicating a deactivated downlink BWP in thecertain serving cell, the terminal apparatus 1 may perform switching ofthe activated downlink BWP from a downlink BMP to another downlink BWPindicated by information indicating the downlink BWP, in the certainserving cell.

In an activated downlink BWP in a certain serving cell, the terminalapparatus 1 may not switch, based on the reception of the downlinkcontrol information including the BWP index information indicating thedeactivated downlink BWP in the other serving cell, the activateddownlink BWP in the certain serving cell.

FIG. 8 is a diagram illustrating an example of a downlink BWP of asecondary cell according to the present embodiment.

830 is the bandwidth of the secondary cell. The bandwidth 830 includesdownlink BWPs 831, 832, 833, and 834. The downlink BWP 832 may be adefault downlink BWP. The downlink BWPs 831, 833, and 834 may benon-default downlink BWPs.

The numeral 840 denotes a period during which the downlink BWP 832 isactivated. The numeral 841 denotes a period during which the downlinkBWP 833 is activated. The numeral 842 denotes a period during which thedownlink BWP 834 is activated. The numeral 843 denotes a period duringwhich the downlink BWP 831 is activated.

Based on the downlink BWPs 831, 832, 833, and 834 being deactivated, andreceiving the activation/deactivation MAC CE indicating the activationof the secondary cell, the terminal apparatus 1 may activate the defaultdownlink BWP 832.

Based on the default downlink BWP 832 being activated, the downlink BWPs831, 833, and 834 being deactivated, and receiving theactivation/deactivation MAC CE indicating the activation of thesecondary cell, the terminal apparatus 1 may activate the defaultdownlink BWP 832.

(850) Based on detecting the PDCCH including the BWP index indicatingthe downlink BWP 833 in the downlink BWP 832 in 840, the terminalapparatus 1 may deactivate the activated downlink BWP 832 and activatethe deactivated downlink BWP 833.

(851) Based on detecting the PDCCH including the BWP index indicatingthe downlink BWP 834 in the downlink BWP 833 in 841, the terminalapparatus 1 may deactivate the activated downlink BWP 833 and activatethe deactivated downlink BWP 834.

(852) Based on detecting the PDCCH including the BWP index indicatingthe downlink BWP 831 in the downlink BWP 834 in 842, the terminalapparatus 1 may deactivate the activated downlink BWP 834 and activatethe deactivated downlink BWP 831.

Based on the reception of the activation/deactivation MAC CE indicatingthe deactivation of the secondary cell in 843, the terminal apparatus 1may deactivate the downlink BWP 831.

80X (X=1, 2, 3, 4), 81Y (Y=1, 2, 3, 4) and, 82Z (1, 2) are CORESETs. Theterminal apparatus 1 monitors a PDCCH in a CORESET. 80X corresponds to aconfiguration of the first CORESET. 81Y corresponds to a configurationof the second CORESET. 82Z corresponds to a configuration of the thirdCORESET. The configuration of CORESET may indicate at least thebandwidth of CORESET, the number of OFDM symbols constituting CORESET,and/or the cycle of CORESET.

The downlink BWP 831 corresponds to the configuration of the secondCORESET and the configuration of the third CORESET. The downlink BWP 832corresponds to the configuration of the first CORESET. The downlink BWP833 corresponds to the configuration of the second CORESET. The downlinkBWP 834 corresponds to the configuration of the first CORESET.

In a case that the downlink BWP 831 is activated, the terminal apparatus1 may monitor the PDCCH in the second CORESET (813, 814) correspondingto the configuration of the second CORESET and the third CORESET (821,822) corresponding to the configuration of the third CORESET.

In a case that the downlink BWP 832 is activated, the terminal apparatus1 may monitor the PDCCH in the first CORESET (801, 802) corresponding tothe configuration of the first CORESET.

In a case that the downlink BWP 833 is activated, the terminal apparatus1 may monitor the PDCCH in the second CORESET (811, 812) correspondingto the configuration of the second CORESET.

In a case that the downlink BWP 834 is activated, the terminal apparatus1 may monitor the PDCCH in the first CORESET (803, 804) corresponding tothe configuration of the first CORESET.

Hereinafter, control resource set (CORESET) will be described.

FIG. 9 is a diagram illustrating an example of a CORESET according tothe present embodiment. In the time domain, the CORESET may be includedin the first OFDM symbol of the slot. The CORESET may be constituted bymultiple resource elements contiguous in the frequency domain. TheCORESET may be constituted by multiple CCEs. One CCE may be constitutedby six contiguous REGs in the frequency domain. One REG may beconstituted by 12 contiguous resource elements in the frequency domain.

FIG. 10 is a diagram illustrating an example of a search space accordingto the present embodiment. The search space is a set of PDCCHcandidates. The PDCCH is transmitted in a PDCCH candidate. The terminalapparatus 1 attempts to decode a PDCCH in the search space. The PDCCHcandidate may be constituted by one or multiple continuous CCEs. Thenumber of CCEs constituting the PDCCH candidate is also referred to asan aggregation level. The search space may be defined for eachaggregation level. The search space 10A includes PDCCH candidates 10AAhaving an aggregation level of 16. The search space 10B includes PDCCHcandidates 10BA and 10BB, each having an aggregation level of 8.

Hereinafter, various aspects of the terminal apparatus 1 and the basestation apparatus 3 according to the present embodiment will bedescribed.

(1) A first aspect of the present embodiment is a terminal apparatus 1including: a receiver configured to receive an activation/deactivationMAC CE indicating activation of a secondary cell, and a medium accesscontrol layer processing unit configured to activate a first downlinkBWP of multiple downlink BWPs, based at least on the reception of theactivation/deactivation MAC CE, and none of the multiple downlink BWPsincluded in the secondary cell being activated. For example, in a casethat the MAC CE indicating the activation of the secondary cell isreceived, the terminal apparatus 1 may activate the default downlink BWP832, based at least on all of the downlink BWPs 831, 832, 833, and 834in the secondary cell being not activated.

(2) In the first aspect of the present embodiment, the medium accesscontrol layer processing unit does not activate the first downlink BWPeven in a case that the activation/deactivation MAC CE is received, in acase that a downlink BWP other than the first downlink BWP is activatedin the multiple downlink BWPs. For example, in a case that any of thenon-default downlink BWPs 831, 833, and 834 included in the secondarycell has already been activated, the default downlink BWP 832 may not beactivated, based on the reception of the activation/deactivation MAC CEindicating the activation of the secondary cell. For example, in a casethat the default downlink BWP 832 included in the secondary cell hasalready been activated, the default downlink BWP 832 may or may not bereactivated, based on the reception of the activation/deactivation MACCE indicating the activation of the secondary cell.

(3) In the first aspect of the present embodiment, each of the multipledownlink BWPs corresponds to an index, and the first downlink BWPcorresponds to the smallest index. The RRCConnectionReconfigurationmessage 605 may include information indicating an index of a downlinkBWP.

(4) In the first aspect of the present embodiment, the first downlinkBWP is indicated by a parameter (RRCConnectionReconfiguration message605) received from the base station apparatus.

(5) A second aspect of the present embodiment is a base stationapparatus 3 including: a transmitter configured to transmit anactivation/deactivation MAC CE indicating activation of a secondary cellto a terminal apparatus; and a medium access control layer processingunit configured to control a downlink BWP to be activated in multipledownlink BWPs included in the secondary cell by transmitting theactivation/deactivation MAC CE, wherein a first downlink BWP in themultiple downlink BWPs is activated by the terminal apparatus, based atleast on the reception of the activation/deactivation MAC CE, and noneof the multiple downlink BWPs included in the secondary cell beingactivated.

(6) A third aspect of the present embodiment is a terminal apparatus 1including: a receiver configured to receive an activation/deactivationMAC CE indicating activation of a secondary cell; and a medium accesscontrol layer processing unit configured to activate a function relatedto monitoring of a PDCCH in a first CORESET set, based at least on thereception of the activation/deactivation MAC CE, and none of themultiple downlink BWPs included in the secondary cell being activated,wherein the first CORESET includes one or more of multiple CORESETsincluded in the secondary cell. The first CORESET set corresponds to theconfiguration of the first CORESET. For example, the first CORESET setmay include the CORESETs 801 and 802. Activating a downlink BWP isactivating a function related to monitoring of a PDCCH in one or moreCORESETs belonging to the downlink BWP.

(7) In a third aspect of the present embodiment, the medium accesscontrol layer processing unit is configured to: based on BWP indexinformation included in a PDCCH detected in the first CORESET set,deactivate a function related to the monitoring of the PDCCH in thefirst CORESET set; and activate a function related to the monitoring ofthe PDCCH in a second CORESET set, wherein the second CORESET setincludes one or more of multiple CORESETs included in the secondarycell. The second CORESET set corresponds to the configuration of thesecond CORESET. For example, the second CORESET set may include theCORESETs 811 and 812.

(8) In the third aspect of the present embodiment, in a case that afunction related to monitoring of a PDCCH in a set of CORESET differentfrom the first CORESET set is activated, even in a case that theactivation/deactivation MAC CE is received, the function related to themonitoring of the PDCCH in the first CORESET set is not activated,wherein the set of CORESET different from the first CORESET set includesone or more of multiple CORESETs included in the secondary cell. Forexample, in a case that an activation/deactivation MAC CE indicatingactivation of a secondary cell is received, a function related tomonitoring of a PDCCH in the first CORESET set may not be activated, ina case that a function related to monitoring of a PDCCH in a secondCORESET set and/or a third CORESET set has already been activated. Forexample, in a case that an activation/deactivation MAC CE indicatingactivation of a secondary cell is received, a function related tomonitoring of a PDCCH in a CORESET AAA may not be activated, in a casethat a function related to monitoring of a PDCCH in a CORESET BBB inCORESETs AAA, BBB, and CCC has already been activated. The third CORESETset corresponds to the configuration of the third CORESET. For example,in a case that the function related to the monitoring of the PDCCH inthe second CORESET set 813 and 814 and the third CORESET set 821 and 822has already been activated, even in a case that theactivation/deactivation MAC CE indicating the activation of thesecondary cell is received, the function related to the monitoring ofthe PDCCH in the first CORESET set corresponding to the configuration ofthe first CORESET may not be activated.

(9) A fourth aspect of the present embodiment is a base stationapparatus 3 including: a transmitter configured to transmit anactivation/deactivation MAC CE indicating activation of a secondary cellto a terminal apparatus; and a medium access control layer processingunit configured to control a CORESET for which a function related tomonitoring of a PDCCH is activated by the terminal apparatus in multipleCORESETs included in the secondary cell, by transmitting theactivation/deactivation MAC CE, wherein a function related to monitoringof a PDCCH in a first CORESET set is activated by the terminalapparatus, based at least on the reception of theactivation/deactivation MAC CE, and none of the multiple downlink BWPsincluded in the secondary cell being activated, and the first CORESETincludes one or more of multiple CORESETs included in the secondarycell.

According to the above, the terminal apparatus 1 and the base stationapparatus 3 are capable of efficiently perform the downlink transmissionand reception.

A program running on the base station apparatus 3 and the terminalapparatus 1 according to an aspect of the present invention may be aprogram that controls a Central Processing Unit (CPU) and the like, suchthat the program causes a computer to operate in such a manner as torealize the functions of the above-described embodiment according to anaspect of the present invention. The information handled in thesedevices is temporarily stored in a Random Access Memory (RAM) whilebeing processed. Thereafter, the information is stored in various typesof Read Only Memory (ROM) such as a Flash ROM and a Hard Disk Drive(HDD), and when necessary, is read by the CPU to be modified orrewritten.

Note that the terminal apparatus 1 and the base station apparatus 3according to the above-described embodiment may be partially achieved bya computer. In that case, this configuration may be realized byrecording a program for realizing such control functions on acomputer-readable recording medium and causing a computer system to readthe program recorded on the recording medium for execution.

Note that it is assumed that the “computer system” mentioned here refersto a computer system built into the terminal apparatus 1 or the basestation apparatus 3, and the computer system includes an OS and hardwarecomponents such as a peripheral apparatus. Furthermore, the“computer-readable recording medium” refers to a portable medium such asa flexible disk, a magneto-optical disk, a ROM, a CD-ROM, and the like,and a storage apparatus such as a hard disk built into the computersystem.

Moreover, the “computer-readable recording medium” may include a mediumthat dynamically retains a program for a short period of time, such as acommunication line that is used to transmit the program over a networksuch as the Internet or over a communication line such as a telephoneline, and may also include a medium that retains a program for a fixedperiod of time, such as a volatile memory within the computer system forfunctioning as a server or a client in such a case. Furthermore, theprogram may be configured to realize some of the functions describedabove, and also may be configured to be capable of realizing thefunctions described above in combination with a program already recordedin the computer system.

Furthermore, the base station apparatus 3 according to theabove-described embodiment may be achieved as an aggregation (apparatusgroup) including multiple apparatuses. Each of the apparatusesconstituting such an apparatus group may include some or all portions ofeach function or each functional block of the base station apparatus 3according to the above-described embodiment. The apparatus group isrequired to have each general function or each functional block of thebase station apparatus 3. Furthermore, the terminal apparatus 1according to the above-described embodiment can also communicate withthe base station apparatus as the aggregation.

Furthermore, the base station apparatus 3 according to theabove-described embodiment may serve as an Evolved Universal TerrestrialRadio Access Network (EUTRAN). Furthermore, the base station apparatus 3according to the above-described embodiment may have some or allportions of the functions of a node higher than an eNodeB.

Furthermore, some or all portions of each of the terminal apparatus 1and the base station apparatus 3 according to the above-describedembodiment may be typically achieved as an LSI which is an integratedcircuit or may be achieved as a chip set. The functional blocks of eachof the terminal apparatus 1 and the base station apparatus 3 may beindividually achieved as a chip, or some or all of the functional blocksmay be integrated into a chip. Furthermore, a circuit integrationtechnique is not limited to the LSI, and may be realized with adedicated circuit or a general-purpose processor. Furthermore, in a casewhere with advances in semiconductor technology, a circuit integrationtechnology with which an LSI is replaced appears, it is also possible touse an integrated circuit based on the technology.

Furthermore, according to the above-described embodiment, the terminalapparatus has been described as an example of a communication apparatus,but the present invention is not limited to such a terminal apparatus,and is applicable to a terminal apparatus or a communication apparatusof a fixed-type or a stationary-type electronic apparatus installedindoors or outdoors, for example, such as an Audio-Video (AV) apparatus,a kitchen apparatus, a cleaning or washing machine, an air-conditioningapparatus, office equipment, a vending machine, and other householdapparatuses.

The embodiments of the present invention have been described in detailabove referring to the drawings, but the specific configuration is notlimited to the embodiments and includes, for example, an amendment to adesign that falls within the scope that does not depart from the gist ofthe present invention. Furthermore, various modifications are possiblewithin the scope of one aspect of the present invention defined byclaims, and embodiments that are made by suitably combining technicalmeans disclosed according to the different embodiments are also includedin the technical scope of the present invention. Furthermore, aconfiguration in which constituent elements, described in the respectiveembodiments and having mutually the same effects, are substituted forone another is also included in the technical scope of the presentinvention.

INDUSTRIAL APPLICABILITY

An aspect of the present invention can be utilized, for example, in acommunication system, communication equipment (for example, a cellularphone apparatus, a base station apparatus, a wireless LAN apparatus, ora sensor device), an integrated circuit (for example, a communicationchip), or a program.

REFERENCE SIGNS LIST

-   1 (1A, 1B, 1C) Terminal apparatus-   3 Base station apparatus-   10 Radio transmission and/or reception unit-   11 Antenna unit-   12 RF unit-   13 Baseband unit-   14 Higher layer processing unit-   15 Medium access control layer processing unit-   16 Radio resource control layer processing unit-   30 Radio transmission and/or reception unit-   31 Antenna unit-   32 RF unit-   33 Baseband unit-   34 Higher layer processing unit-   35 Medium access control layer processing unit-   36 Radio resource control layer processing unit

The invention claimed is:
 1. A terminal apparatus that performscommunication via a primary cell and a secondary cell, the terminalapparatus comprising: reception circuitry configured to receive anactivation/deactivation Medium Access Control (MAC) Control Element (CE)indicating activation of the secondary cell; and medium access controllayer processing circuitry configured to: activate a first downlinkbandwidth part (BWP) in multiple downlink BWPs included in the secondarycell in a case that the activation/deactivation MAC CE is received andthe secondary cell has not been activated, and not to activate the firstdownlink BWP in a case that the activation/deactivation MAC CE isreceived, and the secondary cell and a second downlink BWP of thesecondary cell have been activated before the activation/deactivationMAC CE is received, wherein the first downlink BWP is different from thesecond downlink BWP.
 2. The terminal apparatus according to claim 1,wherein activating the first downlink BWP is indicated by a RadioResource Control (RRC) message received from a base station apparatus.3. A base station apparatus that performs communication via a primarycell and a secondary cell, the base station apparatus comprising:transmission circuitry configured to transmit an activation/deactivationMedium Access Control (MAC) Control Element (CE) indicating activationof the secondary cell to a terminal apparatus; and medium access controllayer processing circuitry configured to control a downlink bandwidthpart (BWP) to be activated in multiple downlink BWPs included in thesecondary cell by transmitting the activation/deactivation MAC CE,wherein: a first downlink BWP in the multiple downlink BWPs is activatedby the terminal apparatus in a case that the terminal apparatus receivesthe activation/deactivation MAC CE and the secondary cell has not beenactivated, the first downlink BWP in the multiple downlink BWPs is notactivated by the terminal apparatus in a case that the terminalapparatus receives the activation/deactivation MAC CE, and the secondarycell and a second downlink BWP of the secondary cell have been activatedbefore the activation/deactivation MAC CE is received, and the firstdownlink BWP is different from the second downlink BWP.
 4. The basestation apparatus according to claim 3, wherein activating the firstdownlink BWP is indicated by transmitting a Radio Resource Control (RRC)message.
 5. A communication method used for a terminal apparatus thatperforms communication via a primary cell and a secondary cell, thecommunication method comprising: receiving an activation/deactivationMedium Access Control (MAC) Control Element (CE) indicating activationof the secondary cell; activating a first downlink bandwidth part (BWP)in multiple downlink BWPs included in the secondary cell in a case thatthe activation/deactivation MAC CE is received and the secondary cellhas not been activated; and not activating the first downlink BWP in acase that the activation/deactivation MAC CE is received, and thesecondary cell and a second downlink BWP of the secondary cell have beenactivated before the activation/deactivation MAC CE is received, whereinthe first downlink BWP is different from the second downlink BWP.
 6. Acommunication method used for a base station apparatus that performscommunication via a primary cell and a secondary cell, the communicationmethod comprising: transmitting an activation/deactivation Medium AccessControl (MAC) Control Element (CE) indicating activation of thesecondary cell to a terminal apparatus; and controlling a downlinkbandwidth part (BWP) to be activated in multiple downlink BWPs includedin the secondary cell by transmitting the activation/deactivation MACCE, wherein: a first downlink BWP in the multiple downlink BWPs isactivated by the terminal apparatus in a case that the terminalapparatus receives the activation/deactivation MAC CE and the secondarycell has not been activated, the first downlink BWP in the multipledownlink BWPs is not activated by the terminal apparatus in a case thatthe terminal apparatus receives the activation/deactivation MAC CE, andthe secondary cell and a second downlink BWP of the secondary cell havebeen activated before the activation/deactivation MAC CE is received,and the first downlink BWP is different from the second downlink BWP.